Process of treating fine ores.



UNITED STATES Patented May 2, 1905.

PATENT OEEIcE,

DAVID BAKER AND WILLIAM W. HEARNE, OF WAYNE, PENNSYLVANIA.

PROCESSOF TREATING FINE ORES;

SPEGIFICATIGN forming part of Letters Patent No. 788,813, dated May 2,1905.

Application filed February 3, 1905. Serial No. 2%,986.

To (ZZZ whom, it may concern:

Be it known that we, DAVID BAKER and TIL- LIAM W. H nAENn,citizens ofthe United States, and residents of Wayne, county of Delaware, State ofPennsylvania,have in vented a new and useful Process of Treating FineIron Ores, of which the following is a specification.

Our invention relates to a new and useful process of treating fine oresor residuessuch as magnetic concentrates or the iron ore variously knownas pyrites residuum, pyri-tes cinders, purple ore, and blue billy torender the same suitable for blast-furnaces.

The object of our invention is to render valuable for the manufacture ofiron the large and important classes of iron-bearing ores that are nowpractically valueless on account of the finely-divided state of suchores or on account both of their large sulfur content, and theirfinely-divided state.

With respect to the fine ores in which sulfur is not present inobjectionable quantities, but where the ore is so finely divided as tocause loss in the smelting and expensive slips and irregularproduct, itis necessary to change the mechanical characteristic of this ore beforethe same can be advantageously used in blast-furnaces. Various methodshave been employed to treat such ore to render it suitable forblast-furnaces for example, the mixing therewith of lime or clay orsimilar materials, grinding the same together, and moisteningthe mixturesufficiently to render it pasty, so that it may be briqueted. Anothermethod is to mix with the ore salt or slag or other fluxing material andthen to burn the mixture to agglomerate it. It will be obvious that aprocess which will agglomerate this fine ore without the admixturetherewith of a flux or hinder will result in enormous saving of time andexpense when large quantities of the ore are so treated, for it is wellknown that the admixture with the ore of a fluxing material requires thetransportation very often of said flexing material to the place wherethe ore is to be treated, the grinding or otherwise preparing of thefluxing material, and the proper mixing of the same with the ore, whichadmixture will vary to suit different qualities of the ore. It will alsobe obterials of each particle of ore-dust.

vious that the use of said fluxing material will involve a substantialincrease of fuel consumption in the subsequent smelting operation, dueto the extra heat required to smelt these additions of flux, all ofwhich implies the consumption of time and money and the employment ofspecial apparatus.

Our process obviates the necessityof mixing a separate fluxing materialwith the ore. Instead of this it utilizes the constituent ma- Theseparticles contain, intimately combined with the iron oxid, suchimpurities as alumina, silica. lime, magnesia; &c. The mass of oredustis subjected to a heat which shall melt these impurities, forming afusible mass with the oxid of iron, or the fusion may be con fined tosuch parts thereof as lie upon and near the surface of the particlesuntil said surfaces become soft or semiplastic and sticky, therebycausing the particles to adhere one to another. The degree of heat neednot be such as would be necessary to melt the iron oxid alone, since thecombination thereof with the other impurities mentioned, in accordancewith a well-known metallurgical law, will melt at a much lowertemperature than each would separately. The rolling agitation of themass causes the formation of lumps or nodules of suitable size forblast-furnace treatment. With respect to the fine ores which have alarge sulfur content it is also necessary to remove the excess of sulfurto render the subsequent smelting process simpler and cheaper, forthesmelting operation being carried on in a reducing-atmosphere willonly partially remove this very objectionable impurity. It is then alsoimportant to agglomerate this fine dusty material to prevent loss insmelting and expensive slips and irregular product which, as is wellknown, result when smelting fine ore.

We are well aware that it is not new to desulfurize ore; but we believewe are the first to employ the process which consists in agitating thematerial at a temperature low enough to prevent the sulfid of iron frommelting and at the same time maintaining strongly-oxidizing conditions.The agitation of the mass during the process of desulfurization is ofthe utmost importance, since it serves to bring every particle of saidmass into contact with the atmosphere, upon which condition theefficiency of the desulfurization depends. When the desulfurization ofthe mass is complete, by increasing the temperature to which said massis subjected theprincipal metallic oxid will fuse with the other oxidscontained in said ore. This will result in an agglomeration of the mass,and by the agitation thereof the same will be broken into sizes suitablefor furnace use.

It is Well known that sulfid ores melt into clinker very easily; butthismelting or clinke ering will prevent the escape of the sulfur, sothat it is important that the-desulfurization be carried on at a lowtemperature an d, finally, when the desulfurization iscomplete, todepend on the increased temperature to-cause the impurities which, asabove. stated, are al ways present in such materials to furnishthe fluxto agglomerate the iron oxid with which such impurities are intimatelymixed.

By our process we not only eliminate the sulfur contained in the ore,but we also secure without the adding of slag or any other fluxingmaterial the agglomeration of the ore in a state suitable forblast-furnace treatment.

We prefer to use for our process a long ro tary kiln, such as is used inthe manufacture of cement, for we can, by charging the material at thecold end, complete the desulfurization before the material reaches thezone of highest temperature, where the clinkering takes place. It wouldbe possible, however, to use a shorter kiln and vary the tempera.- tureas required by the process. With respect to. some materials or ores ourprocess may be facilitated by moistening the ore before charging. itinto the kiln.

What we claim is 1. The process of agglomerating fine iron ores orresidues,.which consists in subjecting the same to atemperature whichshall cause the particles thereof, due to the impurities containedtherein, to fuse sufficiently to become semiplastic and sticky, and toagitate, by rolling the mass, when in the semiplastic state.

2. The process of desulfurizing and agglomerating fine iron ores orresidues, which consists in eliminating the sulfur by means of anoxidizing atmosphere. at a temperature best suited for that purpose, andthen moving the mass into a temperature which shall cause the particlesthereof, due to the impurities contained therein, to fuse sufficientlyto become semiplastic and sticky, and to agitate the mass by revolvingit about ahorizontal .or inclined axis.

3.. The process of agglomerating fine iron ores or residues, whichconsists in passing the same through a: rotating kilnhaving a region inwhich the degree of temperature shall cause the particles thereof, dueto the impurities contained therein, to fuse sufficiently to becomesemiplastic and sticky.

4. The process of desulfurizing and agglomerating fineiron oresorresidues, which consistsin passing the same through a rotating kiln, inone part of which it shall be exposed to an oxidizing atmosphere atatemperature best. suitedfor. its desulfurization,,and in another partof which it shall be exposed to a temperature which shall cause theparticles thereof; due to the impurities contained therein, to fusesuificiently to become semiplastic andsticky.

5. The process of agglomerating' fine iron ores-or: residues, whichconsists'in first moistening the mass and then subjecting the same to -atemperaturewhichshall cause the particles"ther.eof,.due to theimpurities contained therein, tov fuse sufficiently to becomesemiplastic and sticky, and to agitate by rolling the mass when in thesemiplastic state.

6. The processof agglomerating fine'iron oresor residueswhich consistsin first moistening the mass and then passing the same through arotatingkiln having aregion in which the degree of temperature shall cause theparticles thereof, due to the impurities contained therein, to fusesufficiently to become semiplastic and sticky..

7. The-process of desulfurizing and agglomerating fine ironores orresidues which consists in first; moistening the mass and then passingthe same'through a rotating kiln in one-part: of which it shall .beexposed to an oxidizing atmosphere at a temperature best suitedforits-desulfurization and in another partof which it shall be exposedto atemperature which shall cause the particles thereof, due to theimpurities contained therein, to melt .sufliciently to'becomesemiplastic and sticky.

DAVID BAKER. WILLIAM W. HEARNE. Witnesses:

BLANGHE F. MARTIN, LILLIAN M. HUDNUT.

